The release of the collagenase activating factor from mast cells will be investigated by determining changes in collagen after incubation with inactive tissue collagenase and supernates of challenged mast cells. Mast cells will be challenged by IgE mediated responsed, immune complexes and oral bacteria. Immune complexes can cause osteoclastic activity. Human gingival tissue extracts will be examined by the Raji assay for immune complexes. The role of in vivo coating of subgingival bacteria with immunoglobulins and complement in te modulation of the bacteria will be considered. Immunofluorescence will be employed to identify specific subgingival bacteria, the percentage coated with immunoglobulins and complement and serum antibody titers to the specific bacteria. Sera and biopsies from patients with desquamative gingivitis will be examined by immunofluorescence to elucidate the role of these tests in the diagnosis of this disease.